Android 访问网络图片（弱引用访问）

package com.example.leiyan_tupian;

import java.io.IOException;

import java.io.InputStream;

import java.lang.ref.WeakReference;

import java.net.MalformedURLException;

import java.net.URL;

import android.app.Activity;

import android.graphics.Bitmap;

import android.graphics.BitmapFactory;

import android.os.Bundle;

import android.os.Handler;

import android.os.Message;

import android.view.View;

import android.view.View.OnClickListener;

import android.widget.Button;

import android.widget.ImageView;

public class MainActivity extends Activity {

public ImageView iv;

private final MyHandler handler = new MyHandler(this);

private static final int LOAD_SUCCSS = 0x1;

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

Button bt1 = (Button) findViewById(R.id.button1);

iv = (ImageView) findViewById(R.id.imageView1);

bt1.setOnClickListener(new OnClickListener() {

public void onClick(View v) {

new Thread(new Runnable() {

public void run() {

try {

URL url = new URL(

"http://pic2.ooopic.com/01/03/51/25b1OOOPIC19.jpg");

InputStream in = url.openStream();

Bitmap bitmap = BitmapFactory.decodeStream(in);

Message msg = handler.obtainMessage(LOAD_SUCCSS,

bitmap);

handler.sendMessage(msg);

} catch (MalformedURLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

} catch (IOException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}

}).start();

}

});

}

private static class MyHandler extends Handler {

private final WeakReference<MainActivity> weakreference;

public MyHandler(MainActivity mainactivity) {

weakreference = new WeakReference<MainActivity>(mainactivity);

}

public void handleMessage(Message msg) {

MainActivity mainActivity = weakreference.get();

if (mainActivity != null) {

switch (msg.what) {

case LOAD_SUCCSS:

mainActivity.iv.setImageBitmap((Bitmap) msg.obj);

break;

}

}

}

}

}